Why I can't assign dynamic data in constructor C#?

I'm a PHP Developer... I need to do a class that can be created and fill of dynamic way, similar to this in PHP.

class Person{
    private $name;
    private $age;

    function __construct($params = array()){
        foreach ($this as $key => $val) {
            $this -> $key = (isset($params[$key])) ? $params[$key] : "";
        }
    }

    function getName(){
        return $this->name;
    }

    function getAge(){
        return $this->age;
    }

    function setName($value){
        $this->name = $value;
    }

    function setAge($value){
        $this->age = $value;
    }
}

I read about the reflection in C#, but I don't find the correct way to do. This is my C# code

public class Person
{
    private String _name { get { return _name; } set { _name = value; } }
    private int _age { get { return _age; } set { _age = value; } }
    public Person()
    {

    }

    public Person(Hashtable _data)
    {
        PropertyInfo[] propertyInfos;
        propertyInfos = typeof(Person).GetProperties(BindingFlags.NonPublic | BindingFlags.Instance);
        foreach (var propInfo in propertyInfos)
        {
            typeof(Person).GetProperty(propInfo.Name).SetValue(this, _data[propInfo.Name]);
        }
    }
}

In runtime I get an Exception

Object reference not set to an instance of an object.

The typeof(Person) I try to change it to this.getType() and I get the same.

I hope that can help me.